Hi Rob,



On 22/07/2020 11:09, Rob wrote:

The problem is that radio-technology nowadays is nowhere near the
technology when the exams where conceived.

However, that does not apply to antennas, the current topic.
For antennas, their matching, and the losses, the theory that you
(should have) learned for your amateur radio exam still applies today.

Euh .. why would this not apply to antennas?



Modern technology allows you to do a lot of new things that are not at
all covered in the exam:

Antenna-related technologies like spacial diversity reception, phased
antenna-arrays) have become easier to implement with SDR.
Using signal-processing, you can much easier modify (e.g. delay) a
signal, and you can change that dynamically and -if needed- several
times a second.

I did talk to somebody at the GNURadio devroom at FOSDEM last year who
wanted to make such a setup to track weather-satellites with a setup
with three fixed antennas and three phase-locked SDR receivers.



The exam mentions antenna-impedance and antenna tuners, but in how many
clubs has there been a workshop on how (say) the hardware and software
of an magnetic loop automatic antenna-tuner actually works.
(I know of one club where this has been done .. :-).


Same thing for tools.
In how many clubs has the topic of (say) antenna simulation tools.
I went to a club where there was a presentation on this topic. I was
actually the only person who took the time to try this out myself
beforehand and who had a real antenna with me.
When after the presentation, I proposed "you know, why don't we do a
workshop on this, say 5 people. Everybody brings an antenna and we can
all together try to create a model of it so we can really learn the tool".
The responds was ... euh .. overwhelming. (sarc)


I've been trying for years now to find somebody who can give a workshop
on how to design a path-antenna. No success.


The same thing for physical design technology (3D printing, CNC milling,
....) for antenna applications.


There now even is technology where an FPGA on the antenna is use to
connect / disconnect parts of an antenna and to control the polarisation
of the antenna.
You can actually do it so fast that you can use it to encode bits of a
digital transmission in the polarisation of a signal. (apparently, 5G
will use this).





Maybe you should listen/join the ZX net, every Sunday 9AM on 3603 kHz,
where this topic is patiently explained time after time by the moderator
Bob ON9CVD. Or check his website or send him a mail asking for some
of the talks he has held their on the topic of antenna matching.

Thx I will contact him.

Perhaps he can help me to understand how an antenna system actually
works from a physics perspective.


73
kristoff - ON1ARF